Tooth filling and facing composition comprising a radiopaque glass and method of using the same

ABSTRACT

A filler composition for tooth filling and facing compositions comprising (1) a finely divided inorganic material, and (2) a barium aluminosilicate glass or other glass having an effective amount of radiopaque oxide that renders the resultant glass radiopaque to X-rays used by dentists. The filler composition is mixed with an organic polymer such as methyl methacrylate to provide a tooth filling and facing composition having an outstanding combination of desirable properties including a color resembling that of natural teeth, a suitable index of refraction, hardness, wear resistance, a relatively low thermal expansion matching that of natural teeth, and being radiopaque to X-rays used by dentists.

United States Patent Dietz [4 1 Oct. 14, 1975 USING THE SAME [75] Inventor: Earl D. Dietz, Toledo, Ohio [73] Assignee: Owens-Illinois, Inc., Toledo, Ohio [22] Filed: Apr. 25, 1972 [21] Appl. No.: 247,293

Related U.S. Application Data [62] Division of Ser. No. 12,109, Feb. 17, 1970,

abandoned.

[52] U.S. Cl. 32/15; 106/35; 260/4247;

260/4249; 260/4252; 260/9981 1 [51] Int. Cl. A6lK 5/08; C08K 3/34; C09K 3/00 [58] Field of Search 32/2, 8, 12, 15; 106/35,

106/52; 260/DIG. 36, 998.11

[56] References Cited UNITED STATES PATENTS 3,266,147 8/1966 Goldman 106/35 X 3,305,371 2/1967 de Lajarte 106/52 3,400,097 9/1968 Weinstein et al. 32/8 X 3,467,534 9/1969 MacDowell 106/52 X 3,503,128 3/1970 Boyd et a1 32/15 3,531,303 9/1970 Bahat 106/52 X 3,559,288 2/1971 Rehberg et a1. 32/15 X FOREIGN PATENTS OR APPLICATIONS 440,302 12/1935 United Kingdom 106/35 23,728 12/196l Japan 106/35 OTHER PUBLICATIONS Journal of the American Ceramic Society, Vol. 33, (2/1950), at pp. 35-44.

Primary Examiner-Allan Lieberman Attorney, Agent, or FirmRichard D. Heberling; E. J. Holler [57] ABSTRACT A filler composition for tooth filling and facing compositions comprising (l) a finely divided inorganic material, and (2) a barium aluminosilicate glass or other glass having an effective amount of radiopaque oxide that renders the resultant glass radiopaque to X-rays used by dentists. The filler composition is mixed with an organic polymer such as methyl methacrylate to provide a tooth filling and facing composition having an outstanding combination of desirable properties including a color resembling that of natural teeth, a suitable index of refraction, hardness, wear resistance, a relatively low thermal expansion matching that of natural teeth, and being radiopaque to X- rays used by dentists.

16 Claims, 1 Drawing Figure TOOTH FILLING AND FACING COMPOSITION COMPRISING A RADIOPAQUE GLASS AND METHOD OF USING THE SAME This is a division application of my copending application Ser. No. 12,109 filed Feb. 17, 1970 and now abandoned.

THE INVENTION The present invention relates to a tooth filling and facing material having a combination of desirable properties including color resembling that of natural teeth, a compatible index of refraction, strength, hardness, a thermal coefficient of expansion matching that of natural teeth, and being radiopaque to X-rays used by dentists. The invention particularly relates to a tooth filling and facing composition having a mixture of finely divided inorganic material and a radiopaque glass as a filler and an organic polymer as a binder.

In the past, there has been a problem in providing a suitable tooth filling and facing composition containing a filler composition and an organic polymer such as polymethyl methacrylate. The tooth filling and facing composition must have a combination of properties that includes a low coefficient of thermal expansion to match that of natural teeth, strength, hardness, wear resistance, a color resembling that of natural teeth, and a compatible index of refraction while providing enough X-ray absorption to allow detection of the filled tooth. It has been difficult to provide a composition having all of the above-described properties, particularly one that has a thermal coefficient of expansion to match that of natural teeth and still is radiopaque to X- rays used by dentists.

It is an object of the present invention to provide a composition for use as a filler in tooth filling and facing compositions in which the filler composition comprises (1) a finely divided inorganic material and (2) a glass having an effective amount of a radiopaque producing oxide that renders the resultant glass radiopaque to X- rays used by dentists, the filler composition being capable of producing an outstanding tooth facing and filling material when mixed with an organic polymer, the resultant tooth repairing material having a combination of properties including a color resembling that of natural teeth, a suitable index of refraction, hardness, strength, wear resistance, a relatively low thermal expansion matching that of natural teeth, and being radiopaque to X-rays.

It is an object of the present invention to provide a filler composition for a tooth filling and facing composition and a method for filling or facing a tooth using the composition.

These and other objects will be apparent from the specification that follows, the appended claims and the drawings in which:

The FIGURE is a ternary compositional diagram of BaOAl O SiO glass systems showing suitable and preferred glasses that are radiopaque to X-rays used by dentists and are adapted for use as fillers in tooth filling and facing compositions.

The present invention provides a filler composition for use as a filler and tooth facing and filling composition comprising a finely divided inorganic material and a glass having an effective amount of a radiopaque producing oxide that renders the resultant glass radiopaque to X-rays used by dentists. The resultant filler composition is incorporated in an organic binder such as an acrylic resin that produces a filling and facing composition that has a color resembling that of natural teeth, has a suitable index of refraction, has desired hardness and wear resistance, has relatively low thermal expansion matching that of natural teeth, and is radiopaque to X-rays used by dentists.

It is preferred that the radiopaque glass filler be a barium aluminosilicate glass with a BaO content greater than about 22.5 percent by weight, such glass rendering the tooth filling and facing composition radiopaque to X-rays used by dentists. Furthermore, the resultant tooth filling and facing composition containing the barium aluminosilicate glass has a desirable color like that of natural teeth, a suitable index of refraction, high strength, wear resistance, a low thermal expansion matching that of natural teeth, and is nontoxic. Generally, the barium aluminosilicate glass is one consisting of BaO, A1 0 and SiO in the relative proportions by weight shown within the area marked by line I of the ternary diagram shown in the FIGURE. It is highly preferred that the radiopaque glass be one consisting essentially of BaO, M 0 and SiO in the relative proportions by weight shown inside the area marked by line II in the ternary diagram shown in the FIGURE. The optimum radiopaque glass is one consisting essentially of about 25-35 parts by weight of SiO 10-20 parts by weight of A1 0 and 50-60 parts by weight of BaO.

As previously indicated, a part of the filler composition is a finely divided inorganic material such as glassceramic material, quartz, fused silica, calcite, calcium carbonate, wollastonite, or other hard, finely divided inorganic filler having generally a mesh size of about 20-400 mesh, and preferably about to 200 mesh.

The filler composition which is inorganic material and the radiopaque glass is used in amounts of about 20-80 parts by weight with about 20-80 parts by weight of an organic polymer binder. The organic polymer is preferably an acrylic resin such as polyethyl methacrylate, polyethyl acrylate and polymethyl methacrylate and it is highly preferred that the resin be polymethyl methacrylate.

The acrylic polymer can be prepared from a monomer or mixtures of monomers having the general formula where R is an alkyl group of 1 to 3 carbon atoms and X is H or an alkyl group of l to 2 carbon atoms. The above acrylic monomers can be used in an amount of about 100 parts by weight with about 2 to 30 parts by weight of another copolymerizable monomer such as styrene, butadiene, ethylene and acrylic acid to provide a suitable polymer for the tooth repairing compositions. Other polymers can be used such as polyvinyl chloride, cellulose acetate, and a styrene acrylonitrile copolymer providing the resultant composition is radiopaque, has the desired color, index of refraction, strength, wear resistance, thermal expansion and is nontoxic. The filler composition itself generally comprises about 50-90 parts-by weight of the glass-ceramic material or other inorganic filler and about lO-SO parts by weight of radiopaque glass. Preferred amounts of the inorganic filler preferably having a low thermal co- INGREDIENTS PER- CENT sio 25 35 Ai,o 10-20 BaO 50-60 An especially useful glass-ceramic for obtaining the best balance of desired properties contains the following ingredients in approximate percent by weight:

INGREDIENTS PER- CENT sio 67 A1 20 Tio 1.7 zio 2 sb,o, .3 CaO 3.5 U 0 4 Na O 0.4 x 0 0.2

An especially useful radiopaque glass is one that contains the following ingredients in approximate percent by weight:

INGREDIENTS PER- CENT SiO 26 M 0 1 8 BaO 56 Although the preferred radiopaque producing oxide by far is barium oxide, it giving the best color and all around properties to the resultant composition, other radiopaque producing oxides such as strontium can be used. Also suitable but not as good as strontium oxide are lanthanum and other rare earth oxides of the lanthanide series, Nos. 57-71 such as samarium oxide, dysprosium oxide and terbium oxide can be used in which the mass absorption coefficient of the element (including scattering) is generally above about 300 and preferably above about 350 for DuKa, 1.5418 A. The mass absorption coefficient of Ba is given as 359 and lanthanum as 378. However, the lanthanum oxide generally imparts some undesirable color to the tooth filling and facing composition as does praseodymium oxide.

The following example illustrates the present invention.

EXAMPLE A series of filler compositions comprising 30 parts by weight of a barium aluminosilicate glass mixed with 70 parts by weight of a glass-ceramic were prepared and the resultant filler compositions mixed in an amount of about 40 parts by weight with 50 parts by weight of a liquid, solvent-soluble, further curable, methyl methacrylate polymer. The glass-ceramic used was one containing the following ingredients in approximate percent by weight:

INGREDIENTS PER- CENT SiO 67 A1 0 20 Tio 1 .7 zro 2 sb o .3 C210 3 .5 U 0 4 Na O 0.4 K 0 0.2

The barium aluminosilicate g'lass used was one of the following series in which the ingredients are given in weight percent and mole percent.

Weight Percent Mole Percent The resultant mixture was used as a tooth facing and filling composition, the mixture being formed to the desired shape and the organic binder being cured by heating or at room temperature to thereby remove the solvent and form a thermoset polymer that binds the finely divided filler within its matrix.

The resultant compositions all had an outstanding combination of properties including a color resembling that of natural teeth, strength, wear resistance, abrasion resistance, a low thermal expansion matching that of natural teeth and were radiopaque to X-rays used by dentists. The mass absorption coefficients were calculated for copper Ka radiation which has a wavelength of about 1.5418 A. From the standpoint of glass processing including a desirable liquidus, compatible index of refraction and absorption coefficient, it is highly preferred that the radiopaque barium aluminosilicate glasses be ones having compositions similar to that of F and G in the above Table. Hence, the optimum glasses contain about 18-32 weight percent SiO 8-22 weight percent Al O and about 56-62 weight percent BaO. Glasses in the barium aluminosilicate system shown in the area bounded by line I of the FIGURE are advantageous because they have low coefficients of thermal expansion in the range of about 55-60 up to 70 or X 10 /C and have an index of refraction similar to that of natural teeth. The calculated X-ray absorption coefficients of the barium aluminum silicate glasses shown in A through G, X and Y in the Table are as follows:

Mass Absorption Linear Absorption Coefficient Density Coefficient A 83.5 2.7 223 B 101 2.9 293 C 106.9 3.2 342 D 129.8 3.5 454 E 121.5 3.2 388 F 148 3.7 548 G 156.3 4.0 626 X 144.8 3.7 536 Y 1 15.8 3.0 348 The mass absorption coefficients for the elements for CuKa, 1.5418 A, were taken from Appendix V, X-RAY DIFFRACTION PROCEDURES, H. P. Klug and I... E. Alexander, John Wiley & Sons, New York 1959.

As seen in the above Table, generally the linear absorption coefficient can be as low as about 200 to 220 although it is preferred that the coefficient be at least about 340 or 350.

As can be noted in an article by R. H. Thomas entitled Equilibrium In a Portion of The Ternary Systems BaOAl O SiO JOURNAL AMERICAN CE- RAMIC SOCIETY, Vol. 33, February 1950, pages 35-44, the liquidus temperatures of the glasses inside the area of line I are within the range of about 1300 to 1700C. and hence are easily melted, processed and formed. The preferred compositions have a liquidus in the range of about 1400 to 1600C.

What is claimed is:

1. The new use for a barium aluminosilicate glass having a BaO content greater than 22.5 percent by weight, said new use comprising the steps of:

a. forming a filling or facing material by combining said barium aluminosilicate glass and a finely divided inorganic material to form a filler composition, and an organic polymer as a binder therefor; said filling or facing material containing about 20-80 parts by weight of said filler composition and 80-20 parts by weight of said organic polymer binder, said parts by weight being based on the total weight of said filling or facing material; and said filler composition containing 50-90 parts by weight of said finely divided inorganic material and -50 parts by weight of said barium aluminosilicate glass, said parts by weight being based on the total weight of said filler composition; and

b. filling or facing a natural tooth with said filler material;

c. whereby the resultant filling is radiopaque to X- rays used by dentists, has a desirable color like that of natural teeth, an index of refraction like that of natural teeth, high strength and wear resistance and a thermal expansion like that of natural teeth and is non-toxic.

2. The new use as defined in claim 1 wherein said barium aluminosilicate glass consists essentially of BaO, A1 0 and SiO; in the relative proportions by weight shown inside the area of line I in the ternary diagram of FIG. 1.

3. The new use defined in claim 2 wherein said barium aluminosilicate glass consists essentially of BaO, A1 0 and SiO in the relative proportions by weight shown inside the area of line II in the ternary diagram of FIG. 1.

4. The new use as defined in claim 1 wherein the barium aluminosilicate glass consists essentially of about 18 to 32 percent by weight SiO about 8 to 22 percent by weight A1 0 and about 56 to 62 percent by weight BaO.

5. The new use as defined in claim 1 wherein the barium aluminosilicate glass consists essentially of about 25 to 35 percent by weight SiO about 10 to 20 percent by weight A1 0 and about 50 to 60 percent by weight BaO.

6. The new use as defined in claim 1 wherein said inorganic material is selected from the group consisting of glass-ceramic material, quartz, fused silica, calcite, CaCO and wolasonite, having a low coefficient of thermal expansion.

7. The new use as defined in claim 6 wherein said glass-ceramic material consists essentially of SiO Li20, N320, K20, C210, Sb203, A1203, ZrO2 and T102.

8. The new use as defined in claim 1 wherein said inorganic material constitutes 60-80 parts by weight and said barium aluminosilicate glass constitutes 20-40 parts by weight, said parts by weight being based upon the total weight of said filler composition.

9. The new use as defined in claim 8 wherein said inorganic material constitutes -75 parts by weight and said barium aluminosilicate glass constitutes 25-30 parts by weight, said parts by weight being based upon the total weight of said filler composition.

10. The new use as defined in claim 1 wherein the particle size of said finely divided inorganic material is between about 20 and 400 mesh.

11. The new use as defined in claim 1 wherein said barium aluminosilicate glass has an X-ray linear absorption coefficient of at least 200.

12. The new use as defined in claim 11 wherein said barium aluminosilicate glass has an X-ray linear absorption coefficient between 223 and 626.

13. The new use as defined in claim 1 wherein said organic polymer binder is an acrylic resin selected from the group consisting of polyethyl methacrylate, polyethyl acrylate, and polymethyl methacrylate.

14. The new use as defined in claim 1 wherein said barium aluminosilicate glass has a coefficient of thermal expansion in the range of about 55 X 10 /C to about X 10" /C.

15. The new use as defined in claim 1 wherein said organic polymer binder is at least one polymer selected from the group consisting of acrylic resin, polyvinyl chloride, cellulose acetate and styrene acrylonitrile copolymer.

16. The new use as defined in claim 1 wherein said organic polymer is a copolymer of an acrylic monomer and another copolymerizable monomer selected from the group consisting of styrene, butadiene, ethylene and acrylic acid. 

1. THE NEW USE FOR A BARUIM ALUMINOSILICATE GLASS HAVING A BAO CONTENT GREATER THAN 22.5 PERCENT BY WEIGHT, SAID NEW USE COMPRISING THE STEPS OF: A. FORMING A FILLING OR FACING MATERIAL BY COMBINING SAID BARIUM ALUMINOSILICATE GLASS AND A FINELY DIVIDED INORGANIC MATERIAL TO FORM A FILLER COMPOSITION, AND AN ORGANIC POLYMER AS A BINGER THEREFOR, SAID FILLING OR FACING MATERIAL CONTAINING ABOUT 20-80 PARTS BY WEIGHT OF SAID FILLER COMPOSITION AND 80-20 PARTS BY WEIGHT OF SAID ORGANIC POLYMER BINDER, SAID PARTS BY WEIGHT BEING BASED ON THE TOTSAL WEIGHT OF SAID FILLING OR FACING MATERIAL, AND SAID FILLER COMPOSITION CONTAINING 50-90 PARTS BY WEIGHT OF SAID FINELY DIVIDED INORGANIC MATERIAL AND 10-50 PARTS
 2. The new use as defined in claim 1 wherein said barium aluminosilicate glass consists essentially of BaO, Al2O3 and SiO2 in the relative proportions by weight shown inside the area of line I in the ternary diagram of FIG.
 1. 3. The new use defined in claim 2 wherein said barium aluminosilicate glass consists essentially of BaO, Al2O3 and SiO2 in the relative proportions by weight shown inside the area of line II in the ternary diagram of FIG.
 1. 4. The new use as defined in claim 1 wherein the barium aluminosilicate glass consists essentially of about 18 to 32 percent by weight SiO2, about 8 to 22 percent by weight Al2O3 and about 56 to 62 percent by weight BaO.
 5. The new use as defined in claim 1 wherein the barium aluminosilicate glass consists essentially of about 25 to 35 percent by weight SiO2, about 10 to 20 percent by weight Al2O3 and about 50 to 60 percent by weight BaO.
 6. The new use as defined in claim 1 wherein said inorganic material is selected from the group consisting of glass-ceramic material, quartz, fused silica, calcite, CaCO3 and wolasonite, having a low coefficient of thermal expansion.
 7. The new use as defined in claim 6 wherein said glass-ceramic material consists essentially of SiO2, Li2O, Na2O, K2O, CaO, Sb2O3, Al2O3, ZrO2 and TiO2.
 8. The new use as defined in claim 1 wherein said inorganic material constitutes 60-80 parts by weight and said barium aluminosilicate glass constitutes 20-40 parts by weight, said parts by weight being based upon the total weight of said filler composition.
 9. The new use as defined in claim 8 wherein said inorganic material constitutes 70-75 parts by weight and said barium aluminosilicate glass constitutes 25-30 parts by weight, said parts by weight being based upon the total weight of said filler composition.
 10. The new use as defined in claim 1 wherein the particle size of said finely divided inorganic material is between about 20 and 400 mesh.
 11. The new use as defined in claim 1 wherein said barium aluminosilicate glass has an X-ray linear absorption coefficient of at least
 200. 12. The new use as defined in claim 11 wherein said barium aluminosilicate glass has an X-ray linear absorption coefficient between 223 and
 626. 13. The new use as defined in claim 1 wherein said organic polymer binder is an acrylic resin selected from the group consisting of polyethyl methacrylate, polyethyl acrylate, and polymethyl methacrylate.
 14. The new use as defined in claim 1 wherein said barium aluminosilicate glass has a coefficient of thermal expansion in the range of about 55 X 10 7/*C to about 75 X 10 7/*C.
 15. The new use as defined in claim 1 wherein said organic polymer binder is at least one polymer selected from the group consisting of acrylic resin, polyvinyl chloride, cellulose acetate and styrene acrylonitrile copolymer.
 16. The new use as defined iN claim 1 wherein said organic polymer is a copolymer of an acrylic monomer and another copolymerizable monomer selected from the group consisting of styrene, butadiene, ethylene and acrylic acid. 